#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int Fib(int n)
{
    if (n <= 2)
    {
        return n;
    }
    else
    {
        {
            return Fib(n - 1) + Fib(n - 2);
        }
    }
}
int main()
{
    int n = 0;
    scanf("%d", &n);
    printf("%d", Fib(n));
    return 0;
}